Abstract

Phosphorus (P) leaching from on-site wastewater treatment systems may contribute to eutrophication. In developed countries the most common on-site treatment technique is septic systems with soil infiltration. However, the current knowledge about long term P removal in soil treatment systems is not well developed and the data used for estimation of P losses from such systems are unreliable.In this study we sampled four filter beds from community-scale soil treatment systems with an age of between 14 and 22 years to determine the long-term P removal and to investigate the chemical mechanisms behind the observed removal. For one site the long-term P removal was calculated using a mass balance approach. After analysis of the accumulated P. it was estimated that on average 12% of the long-term P load had been removed by the bed material. This indicates a low overall capacity of soil treatment systems to remove phosphorus. Batch experiments and chemical speciation modelling indicated that calcium phosphate precipitation was not an important long-term P removal mechanism, with the possible exception of one of the sites. More likely, the P removal was induced by AlPO4 precipitation and/or sorption to poorly ordered aluminium compounds, as evidenced by strong relationships between oxalate-extractable Al and P. (C) 2012 Elsevier B.V. All rights reserved.

Keywords

On-site wastewater treatment; Soil treatment system; Phosphorus; Removal mechanisms; Chemical speciation modelling; Batch experiment

Published in

Journal of Contaminant Hydrology
2012, Volume: 140, pages: 24-33
Publisher: ELSEVIER SCIENCE BV

UKÄ Subject classification

Environmental Management
Soil Science


Publication identifier

DOI: https://doi.org/10.1016/j.jconhyd.2012.08.003

Permanent link to this page (URI)

https://res.slu.se/id/publ/60134